Our paper is organized as follows. Section  reviews model-free control and the corresponding intelligent proportional controller. Following [1]}, Section REF  investigates the relationship with proportional controllers, which should be considered as the backbone of ALINEA. Modeling issues are discussed in Section : The partial differential equation stemming from elementary hydrodynamic conservation laws, some fundamental empirical laws, the space discretization and its use without any fundamental empirical law, the ALINEA and model-free regulation without the critical density. Computer simulations are displayed and commented in Section . Section REF  in particular exhibits the superiority of model-free control in the presence of sudden changes. Section  contains some concluding remarks.
